Notes:1. Supported resolutions and refresh rates of the adapter are entirely dependent on the USB-C host devices and connected display specifications2. If your computer supports 4K@60Hz, while your monitor/TV only supports 4K@30Hz or 1080p, you can only output 4K@30Hz or 1080p rather than 4K@60Hz3. If the resolution of your laptop is higher than the external monitor.For windows: Windows Menu--> Setting--> Display--> Advanced Display Settings, set your laptop's resolution same as or lower the resolution of external monitor.For MacOS: Left-upper Apple icon-->System Preferences-->Displays-->Mirror displays. Then your HDMI monitor would mirror your Mac.